Subduction of South Pacific waters

Abstract

Using existing high-resolution CTD observations, complemented by a large amount of recently available Argo floating data, this study provides a detailed description of the subduction of South Pacific waters. With a significantly improved climatological dataset on the mixed layer properties, we obtain an annual subduction rate of 48.8 Sv (1 SV = 106 M3 s-1) from 1O°S to 60°S in the South Pacific. Two peaks stand out in this subduction rate sorted by winter mixed layer density: one corresponds to the formation of eastern Subtropical Mode Water (STMW) and part of the Subtropical Underwater (SUW) between 25.0 and 25.5 σθ, and the other has a density range between 26.6 and 27.1 σθ, representing the formation of Sub-Antarctic Mode Water and Antarctic Intermediate Water (SAMW/AAIW). The subduction in eastern STMW/SUW range is 12.7 Sv, only slightly smaller than that (14.6 Sv) associated with the SAMW/AAIW. Sandwiched between these two peaks, roughly in the density range between 26.0 and 26.5 σθ, is the southwestern STMW, with a relatively small annual subdution 5.6 Sv. Uncertainties of these estimates are discussed. Copyright 2008 by the American Geophysical Union.